package com.example.gifdemo;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.Paint.Style;

/**
 * Class GifDecoder - Decodes a GIF file into one or more frames. <br>
 * 
 * <pre>
 *  Example:
 *     GifDecoder d = new GifDecoder();
 *     d.read(&quot;sample.gif&quot;);
 *     int n = d.getFrameCount();
 *     for (int i = 0; i &lt; n; i++) {
 *        Bitmap frame = d.getFrame(i);  // frame i
 *        int t = d.getDelay(i);  // display duration of frame in milliseconds
 *        // do something with frame
 *     }
 * </pre>
 * 
 * No copyright asserted on the source code of this class. May be used for any
 * purpose, however, refer to the Unisys LZW patent for any additional
 * restrictions. Please forward any corrections to kweiner@fmsware.com.
 * 
 * @author Kevin Weiner, FM Software; LZW decoder adapted from John Cristy's
 *         ImageMagick. Converted to Android by Matthew Shepard (mattshepard@gmail.com)
 * @version 1.03 November 2003
 * 
 */

public class GifDecoder {

  /**
   * File read status: No errors.
   */
  public static final int STATUS_OK = 0;

  /**
   * File read status: Error decoding file (may be partially decoded)
   */
  public static final int STATUS_FORMAT_ERROR = 1;

  /**
   * File read status: Unable to open source.
   */
  public static final int STATUS_OPEN_ERROR = 2;

  protected BufferedInputStream in;

  protected int status;

  protected int width; // full image width

  protected int height; // full image height

  protected boolean gctFlag; // global color table used

  protected int gctSize; // size of global color table

  protected int loopCount = 1; // iterations; 0 = repeat forever

  protected int[] gct; // global color table

  protected int[] lct; // local color table

  protected int[] act; // active color table

  protected int bgIndex; // background color index

  protected int bgColor; // background color

  protected int lastBgColor; // previous bg color

  protected int pixelAspect; // pixel aspect ratio

  protected boolean lctFlag; // local color table flag

  protected boolean interlace; // interlace flag

  protected int lctSize; // local color table size

  protected int ix, iy, iw, ih; // current image rectangle

  protected Rect lastRect; // last image rect

  protected Bitmap image; // current frame

  protected Bitmap lastImage; // previous frame

  protected ArrayList<Paint> background = new ArrayList<Paint>();

  protected byte[] block = new byte[256]; // current data block

  protected int blockSize = 0; // block size

  // last graphic control extension info
  protected int dispose = 0;

  // 0=no action; 1=leave in place; 2=restore to bg; 3=restore to prev
  protected int lastDispose = 0;

  protected boolean transparency = false; // use transparent color

  protected int delay = 0; // delay in milliseconds

  protected int transIndex; // transparent color index

  protected static final int MaxStackSize = 4096;

  private static final String TAG = "GifDecode";

  // max decoder pixel stack size

  // LZW decoder working arrays
  protected short[] prefix;

  protected byte[] suffix;

  protected byte[] pixelStack;

  protected byte[] pixels;

  protected ArrayList<GifFrame> frames; // frames read from current file

  protected int frameCount;
  
  private DecoderCallBack callBack;
  
  private boolean hadOOM = false;

	/**
	 * decoder 回调函数
	 * 
	 * @author cainli 2013-1-31 下午4:21:18
	 * 
	 */
	public static interface DecoderCallBack {

		public void onGetOneFrame(GifFrame gifFrame, int index, long nextFrameTime);
	}
  
  static class GifFrame {
    public GifFrame(Bitmap im, int del) {
      image = im;
      delay = del;
    }

    public Bitmap image;

    public int delay;
  }

  public void setCallBack(DecoderCallBack callBack) {
	this.callBack = callBack;
}

/**
   * Gets display duration for specified frame.
   * 
   * @param n
   *          int index of frame
   * @return delay in milliseconds
   */
  public int getDelay(int n) {
    //
    delay = -1;
    if ((n >= 0) && (n < frameCount)) {
      delay = ((GifFrame) frames.get(n)).delay;
    }
    return delay;
  }

  /**
   * Gets the number of frames read from file.
   * 
   * @return frame count
   */
  public int getFrameCount() {
    return frameCount;
  }
  
  public  ArrayList<GifFrame> getFrames(){
	  return frames;
  }
  
  public Paint getBackground(int ix){
	  return null;
  }

  /**
   * Gets the first (or only) image read.
   * 
   * @return Bitmap containing first frame, or null if none.
   */
  public Bitmap getImage() {
    return getFrame(0);
  }

  /**
   * Gets the "Netscape" iteration count, if any. A count of 0 means repeat
   * indefinitiely.
   * 
   * @return iteration count if one was specified, else 1.
   */
  public int getLoopCount() {
    return loopCount;
  }

  /**
   * Creates new frame image from current data (and previous frames as specified
   * by their disposition codes).
   */
  protected void setPixels() throws Exception {
    // expose destination image's pixels as int array
    int[] dest = new int[image.getWidth()*image.getHeight()];
    // fill in starting image contents based on last image's dispose code
    if (lastDispose > 0) {
      if (lastDispose == 3) {
        // use image before last
        int n = frameCount - 2;
        if (n > 0) {
          lastImage = getFrame(n - 1);
        } else {
          lastImage = null;
        }
      }

      if (lastImage != null) {
          Canvas cv = new Canvas(image);
          cv.drawBitmap(lastImage, 0, 0, null);// copy pixels
        if (lastDispose == 2) {
          // fill last image rect area with background color
          Paint bkp = new Paint(Paint.FILTER_BITMAP_FLAG);
    	  bkp.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
    	  bkp.setStyle(Style.FILL);
          if (transparency) {
        	  bkp.setColor(0x00000000);// assume background is transparent
          } else {
        	  bkp.setColor(lastBgColor);// use given background color
          }
          cv.drawRect(lastRect, bkp); // replace area
        }
        image.getPixels(dest, 0, image.getWidth(), 0, 0, image.getWidth(), image.getHeight());
      }
    }

    // copy each source line to the appropriate place in the destination
    int pass = 1;
    int inc = 8;
    int iline = 0;
    for (int i = 0; i < ih; i++) {
      int line = i;
      if (interlace) {
        if (iline >= ih) {
          pass++;
          switch (pass) {
          case 2:
            iline = 4;
            break;
          case 3:
            iline = 2;
            inc = 4;
            break;
          case 4:
            iline = 1;
            inc = 2;
          }
        }
        line = iline;
        iline += inc;
      }
      line += iy;
      if (line < height) {
        int k = line * width;
        int dx = k + ix; // start of line in dest
        int dlim = dx + iw; // end of dest line
        if ((k + width) < dlim) {
          dlim = k + width; // past dest edge
        }
        int sx = i * iw; // start of line in source
        while (dx < dlim) {
          // map color and insert in destination
          int index = ((int) pixels[sx++]) & 0xff;
          int c = act[index];
          if (c != 0) {
            dest[dx] = c;
          }
          dx++;
        }
      }
    }
    image.setPixels(dest, 0, image.getWidth(), 0, 0, image.getWidth(), image.getHeight());
  }

  /**
   * Gets the image contents of frame n.
   * 
   * @return Bitmap representation of frame, or null if n is invalid.
   */
  public Bitmap getFrame(int n) {
	  Bitmap im = null;
    if ((n >= 0) && (n < frameCount)) {
      im = ((GifFrame) frames.get(n)).image;
    }
    return im;
  }

  /**
   * Gets image size.
   * 
   * @return GIF image dimensions
   */
  public Dimension getFrameSize() {
    return new Dimension(width, height);
  }
  
  public class Dimension{
	  public int width;
	  public int height;
	  Dimension(int w, int h){
		  width = w;
		  height = h;
	  }
  }

  /**
   * Reads GIF image from stream
   * 
   * @param BufferedInputStream
   *          containing GIF file.
   * @return read status code (0 = no errors)
   */
  public int read(BufferedInputStream is) throws Exception {
    init();
    if (is != null) {
      in = is;
      readHeader();
      if (!err()) {
        readContents();
        if (frameCount < 0) {
          status = STATUS_FORMAT_ERROR;
        }
      }
    } else {
      status = STATUS_OPEN_ERROR;
    }
    try {
      is.close();
    } catch (IOException e) {
    }
    return status;
  }

  /**
   * Reads GIF image from stream
   * 
   * @param InputStream
   *          containing GIF file.
   * @return read status code (0 = no errors)
   */
  public int read(InputStream is) throws Exception {
    init();
    if (is != null) {
      if (!(is instanceof BufferedInputStream))
        is = new BufferedInputStream(is);
      in = (BufferedInputStream) is;
      readHeader();
      if (!err()) {
        readContents();
        if (frameCount < 0) {
          status = STATUS_FORMAT_ERROR;
        }
      }
    } else {
      status = STATUS_OPEN_ERROR;
    }
    try {
      is.close();
    } catch (IOException e) {
    }
    return status;
  }

  /**
   * Reads GIF file from specified file/URL source (URL assumed if name contains
   * ":/" or "file:")
   * 
   * @param name
   *          String containing source
   * @return read status code (0 = no errors)
   */
  public int read(String name) throws Exception {
    status = STATUS_OK;
    try {
      name = name.trim().toLowerCase();
      if ((name.indexOf("file:") >= 0) || (name.indexOf(":/") > 0)) {
        URL url = new URL(name);
        in = new BufferedInputStream(url.openStream());
      } else {
        in = new BufferedInputStream(new FileInputStream(name));
      }
      status = read(in);
    } catch (IOException e) {
      status = STATUS_OPEN_ERROR;
    }

    return status;
  }

  /**
   * Decodes LZW image data into pixel array. Adapted from John Cristy's
   * ImageMagick.
   */
  protected void decodeImageData() {
    int NullCode = -1;
    int npix = iw * ih;
    int available, clear, code_mask, code_size, end_of_information, in_code, old_code, bits, code, count, i, datum, data_size, first, top, bi, pi;

    if ((pixels == null) || (pixels.length < npix)) {
      pixels = new byte[npix]; // allocate new pixel array
    }
    if (prefix == null)
      prefix = new short[MaxStackSize];
    if (suffix == null)
      suffix = new byte[MaxStackSize];
    if (pixelStack == null)
      pixelStack = new byte[MaxStackSize + 1];

    // Initialize GIF data stream decoder.

    data_size = read();
    clear = 1 << data_size;
    end_of_information = clear + 1;
    available = clear + 2;
    old_code = NullCode;
    code_size = data_size + 1;
    code_mask = (1 << code_size) - 1;
    for (code = 0; code < clear; code++) {
      prefix[code] = 0;
      suffix[code] = (byte) code;
    }

    // Decode GIF pixel stream.

    datum = bits = count = first = top = pi = bi = 0;

    for (i = 0; i < npix;) {
      if (top == 0) {
        if (bits < code_size) {
          // Load bytes until there are enough bits for a code.
          if (count == 0) {
            // Read a new data block.
            count = readBlock();
            if (count <= 0)
              break;
            bi = 0;
          }
          datum += (((int) block[bi]) & 0xff) << bits;
          bits += 8;
          bi++;
          count--;
          continue;
        }

        // Get the next code.

        code = datum & code_mask;
        datum >>= code_size;
        bits -= code_size;

        // Interpret the code

        if ((code > available) || (code == end_of_information))
          break;
        if (code == clear) {
          // Reset decoder.
          code_size = data_size + 1;
          code_mask = (1 << code_size) - 1;
          available = clear + 2;
          old_code = NullCode;
          continue;
        }
        if (old_code == NullCode) {
          pixelStack[top++] = suffix[code];
          old_code = code;
          first = code;
          continue;
        }
        in_code = code;
        if (code == available) {
          pixelStack[top++] = (byte) first;
          code = old_code;
        }
        while (code > clear) {
          pixelStack[top++] = suffix[code];
          code = prefix[code];
        }
        first = ((int) suffix[code]) & 0xff;

        // Add a new string to the string table,

        if (available >= MaxStackSize)
          break;
        pixelStack[top++] = (byte) first;
        prefix[available] = (short) old_code;
        suffix[available] = (byte) first;
        available++;
        if (((available & code_mask) == 0) && (available < MaxStackSize)) {
          code_size++;
          code_mask += available;
        }
        old_code = in_code;
      }

      // Pop a pixel off the pixel stack.

      top--;
      pixels[pi++] = pixelStack[top];
      i++;
    }

    for (i = pi; i < npix; i++) {
      pixels[i] = 0; // clear missing pixels
    }

  }

  /**
   * Returns true if an error was encountered during reading/decoding
   */
  protected boolean err() {
    return status != STATUS_OK;
  }

  /**
   * Initializes or re-initializes reader
   */
  protected void init() {
    status = STATUS_OK;
    frameCount = 0;
    frames = new ArrayList<GifFrame>();
    gct = null;
    lct = null;
  }

  /**
   * Reads a single byte from the input stream.
   */
  protected int read() {
    int curByte = 0;
    try {
      curByte = in.read();
    } catch (IOException e) {
      status = STATUS_FORMAT_ERROR;
    }
    return curByte;
  }

  /**
   * Reads next variable length block from input.
   * 
   * @return number of bytes stored in "buffer"
   */
  protected int readBlock() {
    blockSize = read();
    int n = 0;
    if (blockSize > 0) {
      try {
        int count = 0;
        while (n < blockSize) {
          count = in.read(block, n, blockSize - n);
          if (count == -1)
            break;
          n += count;
        }
      } catch (IOException e) {
      }

      if (n < blockSize) {
        status = STATUS_FORMAT_ERROR;
      }
    }
    return n;
  }

  /**
   * Reads color table as 256 RGB integer values
   * 
   * @param ncolors
   *          int number of colors to read
   * @return int array containing 256 colors (packed ARGB with full alpha)
   */
  protected int[] readColorTable(int ncolors) {
    int nbytes = 3 * ncolors;
    int[] tab = null;
    byte[] c = new byte[nbytes];
    int n = 0;
    try {
      n = in.read(c);
    } catch (IOException e) {
    }
    if (n < nbytes) {
      status = STATUS_FORMAT_ERROR;
    } else {
      tab = new int[256]; // max size to avoid bounds checks
      int i = 0;
      int j = 0;
      while (i < ncolors) {
        int r = ((int) c[j++]) & 0xff;
        int g = ((int) c[j++]) & 0xff;
        int b = ((int) c[j++]) & 0xff;
        tab[i++] = 0xff000000 | (r << 16) | (g << 8) | b;
      }
    }
    return tab;
  }

  /**
   * Main file parser. Reads GIF content blocks.
   */
  protected void readContents() throws Exception {
    // read GIF file content blocks
    boolean done = false;
    while (!(done || err())) {
      int code = read();
      switch (code) {

      case 0x2C: // image separator
    	  if(!readImage()){
    		  return;
    	  }
        break;

      case 0x21: // extension
        code = read();
        switch (code) {
        case 0xf9: // graphics control extension
          readGraphicControlExt();
          break;

        case 0xff: // application extension
          readBlock();
          String app = "";
          for (int i = 0; i < 11; i++) {
            app += (char) block[i];
          }
          if (app.equals("NETSCAPE2.0")) {
            readNetscapeExt();
          } else
            skip(); // don't care
          break;

        default: // uninteresting extension
          skip();
        }
        break;

      case 0x3b: // terminator
        done = true;
        break;

      case 0x00: // bad byte, but keep going and see what happens
        break;

      default:
        status = STATUS_FORMAT_ERROR;
      }
    }
  }

  /**
   * Reads Graphics Control Extension values
   */
  protected void readGraphicControlExt() {
    read(); // block size
    int packed = read(); // packed fields
    dispose = (packed & 0x1c) >> 2; // disposal method
    //if (dispose == 0) {
    //  dispose = 1; // elect to keep old image if discretionary
    //}
    transparency = (packed & 1) != 0;
    delay = readShort() * 10; // delay in milliseconds
    transIndex = read(); // transparent color index
    read(); // block terminator
  }

  /**
   * Reads GIF file header information.
   */
  protected void readHeader() {
    String id = "";
    for (int i = 0; i < 6; i++) {
      id += (char) read();
    }
    if (!id.startsWith("GIF")) {
      status = STATUS_FORMAT_ERROR;
      return;
    }

    readLSD();
    if (gctFlag && !err()) {
      gct = readColorTable(gctSize);
      bgColor = gct[bgIndex];
    }
  }

  /**
   * Reads next frame image
   */
  protected boolean readImage() throws Exception  {
	long nextFrameTime = android.os.SystemClock.uptimeMillis() + getDelay();
    ix = readShort(); // (sub)image position & size
    iy = readShort();
    iw = readShort();
    ih = readShort();

    int packed = read();
    lctFlag = (packed & 0x80) != 0; // 1 - local color table flag
    interlace = (packed & 0x40) != 0; // 2 - interlace flag
    // 3 - sort flag
    // 4-5 - reserved
    lctSize = 2 << (packed & 7); // 6-8 - local color table size

    if (lctFlag) {
      lct = readColorTable(lctSize); // read table
      act = lct; // make local table active
    } else {
      act = gct; // make global table active
      if (bgIndex == transIndex)
        bgColor = 0;
    }
    int save = 0;
    if (transparency) {
      save = act[transIndex];
      act[transIndex] = 0; // set transparent color if specified
    }

    if (act == null) {
      status = STATUS_FORMAT_ERROR; // no color table defined
    }

    if (err())
      return false;

    decodeImageData(); // decode pixel data
    skip();

    if (err())
      return false;

    frameCount++;

    try {
    	// create new image to receive frame data
    	image = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_4444);
	} catch (OutOfMemoryError error) {
		/*
		 * 内存溢出了··就不继续解码了
		 * 如果继续创建bitmap 可能继续OOM，
		 * 如果跳下一帧 又会出现gif跳帧，所以直接结束解码
		 */
		hadOOM = true;
		return false ;
		
	}

    setPixels(); // transfer pixel data to image

    GifFrame gifFrame = new GifFrame(image,  getDelay());
    if(callBack!=null){
    	callBack.onGetOneFrame(gifFrame, frameCount,nextFrameTime);
    }
    frames.add(gifFrame); // add image to frame list

    if (transparency) {
      act[transIndex] = save;
    }
    resetFrame();
    
	return true;

  }
  
  /**
   *限制最小的延时
   * @return
   */
  public int getDelay(){
	return   delay < 100 ? 100 : delay;
  }

  /**
   * Reads Logical Screen Descriptor
   */
  protected void readLSD() {

    // logical screen size
    width = readShort();
    height = readShort();

    // packed fields
    int packed = read();
    gctFlag = (packed & 0x80) != 0; // 1 : global color table flag
    // 2-4 : color resolution
    // 5 : gct sort flag
    gctSize = 2 << (packed & 7); // 6-8 : gct size

    bgIndex = read(); // background color index
    pixelAspect = read(); // pixel aspect ratio
  }

  /**
   * Reads Netscape extenstion to obtain iteration count
   */
  protected void readNetscapeExt() {
    do {
      readBlock();
      if (block[0] == 1) {
        // loop count sub-block
        int b1 = ((int) block[1]) & 0xff;
        int b2 = ((int) block[2]) & 0xff;
        loopCount = (b2 << 8) | b1;
      }
    } while ((blockSize > 0) && !err());
  }

  /**
   * Reads next 16-bit value, LSB first
   */
  protected int readShort() {
    // read 16-bit value, LSB first
    return read() | (read() << 8);
  }

  /**
   * Resets frame state for reading next image.
   */
  protected void resetFrame() {
    lastDispose = dispose;
    lastRect = new Rect(ix, iy, iw+ix, ih+iy);
    lastImage = image;
    lastBgColor = bgColor;
    //dispose = 0;
    //transparency = false;
    //delay = 0;
    lct = null;
  }
  
  /**
   * Converts image frames to specified format and stores in separate container.
   * GifDecoder object can be garbage collected afterwards.
   * 
   * Note: Converting to Bitmap.Config.RGB_565 will lose transparency.
   * @param conf Default: Bitmap.Config.ARGB_8888 
   * @return Array of GifFrame objects in specified storage format.
   */
  public GifFrame[] getCompressedArray(Bitmap.Config conf){
	  GifFrame[] out = new GifFrame[frames.size()];
	  for(int x=0;x<frames.size();x++){
		  GifFrame old = frames.get(x);
		  if(conf == null || old.image.getConfig().equals(conf)){
			  out[x]=new GifFrame(old.image, old.delay);
		  }else{
			  out[x]=new GifFrame(old.image.copy(conf, false),old.delay);
		  }
		  old.image.recycle();
	  }
	  return out;
  }
  /**
   * Convenience function to decode gif, convert to specified format, 
   * and return array of GifFrames containing image and delay data.
   * 
   * Note: Using Bitmap.Config.RGB_565 will remove any transparency.
   * @param in InputStream with raw gif data.
   * @param format Bitmap.Config format to store outputed data. (Default: Bitmap.Config.ARGB_8888)
   * @return Array of GifFrame objects. Will return null if OutOfMemoryError occurs.
   */
  public static GifFrame[] decodeGif(InputStream in, Bitmap.Config format){
  	GifFrame[] out = null;
  	try {
  		GifDecoder d = new GifDecoder();
		d.read(in);
		out = d.getCompressedArray(format);
	} catch (Exception e) {
		out = null;
	} catch (OutOfMemoryError oom){
		out = null;
	}
	return out;
  }

  /**
   * Skips variable length blocks up to and including next zero length block.
   */
  protected void skip() {
    do {
      readBlock();
    } while ((blockSize > 0) && !err());
  }
}